Side panel assemblies typically include a front wall, a back wall, and a side panel which extends between the front and back walls to form a housing or enclosure. In many applications, it is desirable to form the side panel of such an assembly from a continuous web of material which is bent to conform to the periphery of the front and/or back walls. Such an assembly may, for example, form a housing for electrical components or a container for articles of various types.
One application of such assemblies is in forming lighted channel letters, words or other designs in the sign industry. In this regard, a lighted channel letter is commonly formed by placing a light or lights within a three-dimensional letter shaped housing. The channel housing normally includes a transparent or translucent front wall or cover and a side wall or channel formed from metal which extends about the outer and/or inner periphery of the letter. The channel thus provides the housing with a depth sufficient to house the light or lights.
In manufacturing channel letters, it is desirable to provide easy access to the internal light source for servicing. In addition, it is desirable to sealably interconnect the channel to the cover and back plate to provide some protection against moisture penetration and undesired light leaks. A further consideration in manufacturing channel letters is minimizing construction material and labor costs. Thus, it is important to achieve ease of access for servicing and sealing protection without unduly complicating channel letter construction or increasing material costs.
One known type of channel letter is depicted in FIG. 1. The channel letter 1 comprises a layered base plate 2 including central wood layer 2b having metal sheets 2a and 2c attached to the major faces thereof; a plastic cover 3;
and a channel 4 extending between said base plate 2 and cover 3. The channel 4 is interconnected to the base plate 2 by inserting a screw, nail or other fastener through the channel 1 into the central layer 2b of base plate 2. In this regard, the base plate 2 is formed with a thickness sufficient to receive the fastener.
The interconnection between the channel 4 and cover 3 can also be seen in FIG. 1. The cover 3 is adhesively affixed to a flexible plastic flange 5 which is oriented substantially perpendicular to the cover 3. During construction, the channel 4 and flange 5 are bent together to form a seam 6 such that the flange 5 is captured within the seamed channel 4. An adhesive and/or sealant may also be applied at the flange/channel interface. Additionally, a strip of foam 7 is attached to the base plate 2 adjacent to the channel 4 to guard against light leaks.
One disadvantage of such channel letters is that they require a relatively thick base plate 2 to receive the screw. This increases the material requirements and costs of manufacturing. In addition, the seaming of the flange and channel 4 is a relatively complicated process and requires that the cover 3 be affixed to the flange 5, thereby further increasing construction costs.
Heretofore, forming the channel of a channel letter has generally been a labor-intensive process in which the required calculations and bending processes were largely performed manually. A channel can be formed from a length of stock material by forming a series of bends, e.g., corners or curves of appropriate shape at the appropriate positions on the stock. In practice, depending on the equipment used to form the bends, curves may be formed by a series of chord-like flat surfaces rather than one continuously curved surface. Several parameters must be considered in bending the channel to the appropriate shape. These parameters include the longitudinal positioning of the bends on the channel stock, the shape of the bends, and the sequence for making the bends. As used herein, the term "shape" includes the total angle of a corner or curve, the radius of curvature of a curve, and other bend characteristics. The material and thickness of the sheet stock may also need to be considered in forming the design.
Upon consideration, it will be appreciated that selecting a sequence for making the bends is problematic. For example, in bending a strip of stock material to form a channel, the bends cannot necessarily be made in the same sequence as they would be in writing the letter. This is because such a sequence might result in mechanical interference between the already bent portions of the stock and the remaining, as yet unbent, portions of the stock or the machinery used to bend the stock. That is, such a sequence might result in the unbent portion of the stock coming into contact with the bent portion or the machinery. Such interference can often be avoided by selection of a suitable sequence for making the bends.
The process of bending a strip of stock material to form a channel has therefore typically required the skill of an experienced operator. Commonly, such an operator would physically measure the front or back wall of the channel letter and use the measurements to determine the shapes and positions of the bends. Thereafter, the operator could often determine an acceptable sequence for making the required bends by drawing on experience and skill or through a trial and error process. The operator then normally manually attached bending instructions regarding the positions, shapes and sequence of the bends directly to the side strip. For example, the instructions could be manually written on the stock or on tape which was then attached to the stock. A machinist could then use the instructions to make the desired bends.
Such manual processes have a number of drawbacks. First, as stated above, such manual processes typically require the skill of an experienced operator to perform measurements, determine an acceptable sequence for making the bends, and provide instructions regarding the positions, shapes and sequence of the bends. In addition, such manual processes are generally time consuming, thereby increasing the manufacturing costs of the channel letter. Moreover, such manual processes are often inexact and highly susceptible to error. Thus, manual processes can be inefficient, costly and inaccurate.
A number of computer numeric controlled machines for bending metal are known. However, these machines do not determine the positions, shapes and sequence of bends for forming stock material into a channel of a channel letter. Such machines, therefore, do not solve the problems discussed above.